A block is undergoing simple harmonic motion $($SHM$)$ at the end of a spring, with its position described by the equation:

x$($t$)=$xmcos$($t$+),$x$($t$)=$ x$\_$m $\backslash$cos$(\backslash$omega t $+\backslash$phi$),$x$($t$)=$xm$$cos$($t$+),$

where xmx$\_$mxm$$ is the amplitude, $\backslash$omega is the angular frequency, and $=0\mathrm{.}992$rad$\backslash$phi $=0\mathrm{.}992\backslash ,\backslash$text$\{$rad$\}=0\mathrm{.}992$rad is the phase constant.

At t$=0$t $=0$t$=0,$ what percentage of the total mechanical energy is stored as potential energy in the system?